Sheet Metal Bend Relief Formula

Refer to the chart for values for folder as well as various press brake tooling combinations.

Sheet metal bend relief formula.

The diagram shows one such mechanism. D 2 5t r see below the height can be less but it required secondary operations and is far more costly. You will need to know your material thickness mt the bend angle b the inside radius ir and the k factor k. To eliminate this a bend relief is added so the edge of the sheet metal is perpendicular to the bend.

Most sheet metal materials will conform to the calculations. The bend deduction sometimes called the bend compensation describes how much the outside of the sheet has been stretched. ß bending angle for bends between 90 and 165 degrees the formula is. Geometry of tooling imposes a minimum bend dimension.

60 90 and 120 and we will calculate k factor bend allowance and bend deduction for them. We are going to review three bending scenarios with three different bending angles. Sheet metal calculator bend allowance equations and calculator. 5 edge distortion an exaggerated example of edge deformation is pictured in figure a below.

Use the minimum bend dimension values in the charts below for your minimum closeness of cutout to a bend. Therefore the bend allowance added to the flange lengths is equal to the total flat length. This page also includes a link to a on line sheet metal bend allowance calculator. The bend allowance describes the length of the neutral axis between the bend lines or in other words the arc length of the bend.

For bends between 0 and 90 degrees the formula is as follows. In general a minimum bend relief is equal to the material thickness plus the inside bend radius. The bend allowance formula takes into account the geometries of bending and the properties of your metal to determine the bend allowance. The material thickness will be measured in decimal form not by the gauge number.

When sheet metal makes a transition from a bend to a flat surface or to another bend it tends to rip and tear. Consider a sheet with a 20 mm thickness and a length of 300 mm as shown in figure 1.